Hi All. I was told once upon a time that you needed to use a "buffer" between safety ground and signal earth to keep the mains noise out of your music. I have made a diagram below as a reference for this thread. Take a look and tell me what you think. I am going to be building a two box preamp and I wanted to get the parts list down so I can see how much the financial damage is going to be. I'm not sure that I need to connect signal earth to safety ground in the circuit chassis. What do you think?

Originally posted by Luke If I understand this correctly, the signal ground of chassis 2 is not connected to chassis ground at all?

Wow, talking about digging up an old post! If you mean Frank's diagram then yes, he is recommending that in the audio circuit chassis, there is no connection from signal ground to chassis, and that this connection only be made in the power supply chassis.

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The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts. Bertrand Russell

yeah I know its an oldie but these issues allways crop up:-)
Ive got something like this and I cant get rid of the hum, Im going to redo the grounding as per this schema and see what happens.
Im terrible with grounding, I allways use star grounds but I think I need to put a bit more thought into it before wiring.
thanks!